| Lake eutrophication is one of the problems of water environment in China.Phosphorus as a key controlling factor of the eutrophication, it is very important forlake eutrophication. It is particularly important for us to study the endogenousphosphorus pollution load and the transforming relationship between sources and sinkin the "Soil-Plant-Water" three phase interface, when the exogenous phosphorusinput to get a certain degree of control. In this paper, taking the Nanjishan NatureReserve of Poyang Lake as the research object and combining field sampling andlaboratory simulation, change trend in the form of soil phosphorus under dry-wetalternate environment with the main encompassment Poyang Lake water levelvariation characteristics is researched; and through the investigation of Nanjishanwetland plant communities with seasons change in the law, transformation and releaseproperties of soil phosphorus in the process of typical wetland plant growth anddecline is analyzed; also the adsorption capacity of soil phosphorus in the NanjishanNature Reserve is studied to investigate the potential risk of soil phosphorus release,to provide basic theory reference for the Poyang Lake eutrophication control. Themain conclusions are as follows:1. Under the condition of continuous flooding, TP, DTP, SRP content showed adownward trend in the overlying water, and the magnitude of each phosphorusconcentration decreased increasing compared to the previous, which is related to thesoil phosphorus adsorption quantity increases after continuous flooding and release ofphosphate on dry off process. Under flooded conditions, the change of Fe/Al-P andOr-P in soil is significant, Or-P content increased, but the Fe/Al-P is the main formof soil phosphorus release. The reaction produced when the soil is dry off is reverseprocess under waterlogged conditions reaction.2. TP concentration when added the HgCl2is lower than the overlying waterphosphorus concentration without HgCl2treatment. With the flooded time increasing,on the whole, the soil TP presents rising trend. TP content in the soil which treated byHgCl2continues to rise and above the TP content in soil contains microbes after flooding10d, after HgCl2treatment TP levels continue to rise above the soil containsmicroorganisms, it is stable at122.75mg/kg in30d.3. TP content in soil and water where is in the region without plants growth ishigher than TP content in flora, this is due to plants grow need absorb and accumulateof phosphorus from the soil and water. TP content of water lower percentage of Nandi,Yeaihao, Shichangpu and the blank group were59.38%,52.63%,40.43%,-23.53%in summer simulation experiments, soil TP content of each group were graduallyreduced, and the reduce percentage were29.97%,29.41%,28.85%,17.71%respectively. After the preliminary analysis，The plants’ capacity to absorb phosphorusduring the growth period showed: Nandi> Yeaihao> Shichangpu. Whether plantswere in growth stage or decline stage, the existence of plants has significant impacton TP content and other forms of phosphorus content in the water and soil. In thisstudy, on the one hand, emergent plants can purify the water quality, on the otherhand they also have the effect of fixing nutrients on soil surface.4. The Nanjishan Nature Reserve wetland soil phosphorus adsorption indexshowed that the characteristics of the plant growth areas on the high side, howeverphosphorus adsorption saturation has little difference between the various points. Poxcontent in the soil was significantly positive correlation with Feox, Aloxand TPcontent. Phosphorus release risk index was applied to evaluate the release of potentialrisk about the Nanjishan Nature Reserve wetland soil Endogenous phosphorus. Theresults show that the soil phosphorus release cause eutrophication in the region withinthe low risk, it is mainly due to the area affected by human factors is small, andkeeping the superior natural environment. |
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